Trees and shrubs, mostly of dry tropical or warm temperate regions. Acacia is a dominant legume genus of tropical deciduous forests and savannas. Economically, there are many uses from different species of this genus. The flowers of A. farnesiana are used in perfumery; A. senegal furnishes most of the gum arabic of commerce; a hair-wash or soap is made from A. cocinna; a drug is made from wood of A. catechu; many have scented wood; others make fine furniture wood; leaves of some species are used in cooking; several are used as forage plants, dyes or fiber and finally, still others are street trees or houseplants.

A famous mutualism: the Acacia provides food and shelter for ants, which in turn protect the plant from herbivores. The shelter is in the form of hollow stipular thorns. The food comes as "Beltian bodies", little globs of oil and protein at the tips of leaflets (look closely). These are named for the "Naturalist of Nicaragua", Thomas Belt.